Paisant Anita, d'Assignies Gaspard, Bannier Elise, Bardou-Jacquet Edouard, Gandon Yves
CHU de Rennes, service de radiologie, 35033 Rennes, France.
CHU de Rennes, service de radiologie, 35033 Rennes, France.
Presse Med. 2017 Dec;46(12 Pt 2):e279-e287. doi: 10.1016/j.lpm.2017.10.008. Epub 2017 Nov 11.
MRI is now the reference method for detecting and quantifying hepatic and extrahepatic iron overload, regardless of its cause. The decrease of the hepatic signal is proportional to the amount of iron in the tissues. It is more pronounced with T2*-weighted gradient echo sequences. It increases proportionally with the strength of the magnetic field. Thus a 3-T MRI is be more sensitive and probably more accurate to detect a slight iron overload, as seen in dysmetabolic hepatosiderosis. Conversely, a 1.5-T MRI better estimates a high overload. Quantification can be done with the calculation of T2* (or R2*) or by using the liver to muscle signal intensity ratio (SIR). Today with a single multi-echo gradient-echo sequence, obtained in a unique apnea, the two methods can be used simultaneously. An associated quantification of steatosis is also obtained. This same type of sequence is proposed for quantification of iron in other tissues and in particular for the myocardium.
磁共振成像（MRI）现在是检测和量化肝内及肝外铁过载的参考方法，无论其病因如何。肝脏信号的降低与组织中的铁含量成正比。在T2加权梯度回波序列中更为明显。它与磁场强度成比例增加。因此，3T MRI在检测轻微铁过载（如在代谢异常性肝铁沉积症中所见）时可能更敏感且可能更准确。相反，1.5T MRI能更好地评估高度过载情况。可以通过计算T2（或R2*）或使用肝脏与肌肉信号强度比（SIR）来进行量化。如今，通过在单次屏气时获得的单个多回波梯度回波序列，可以同时使用这两种方法。还可同时获得脂肪变性的相关量化结果。对于其他组织，特别是心肌中的铁量化，也建议使用相同类型的序列。
